Clutch system for a vehicle

ABSTRACT

A clutch actuation system for a vehicle, comprises a first assembly adapted to be driven from a stop position by an actuating force, and a second assembly, which is driven by the first assembly, and drives in a certain direction a driven member which moves in such a way that a first part of its travel is accomplished against a relatively weak resisting force, and a following part of its travel is accomplished against a relatively strong restoring force. A clearance adjuster comprises means for biasing the first and second assemblies with respect to one another in such a direction as, if the first assembly remains in its stop position, to drive the driven member in said certain direction with biasing force strong enough to overcome said relatively weak resisting force but not strong enough to overcome said relatively strong restoring force, and means for locking the position of said first assembly with respect to said second assembly when said first assembly is moved off its stop position.

BACKGROUND OF THE INVENTION

The present invention relates to a clearance adjuster, and moreparticularly relates to a clearance adjuster for adjusting the clearancein a clutch actuation system for a vehicle in which a clutch pedaldrives a clutch by a cable assembly. In its widest concept, however, theclearance adjuster of the present invention can be used for a wide rangeof devices.

The background of the present invention will be particularly explainedwith respect to its application to such a clutch actuation system.

FIG. 1 of the accompanying drawings shows a conventional clutchactuation system. A clutch pedal 2 drives a clutch assembly 1 via acable assembly consisting of an inner cable 5 and outer cable 7. Theclutch pedal 2 is pivoted on the body of a vehicle by a shaft 8 securedto the vehicle's body by a braket or the like. One arm 4 of the clutchpedal 2 is equipped with a pedal pad 6, so that it can conveniently bestepped on by the vehicle operator and depressed. The other end of theclutch pedal 2 is provided with a notch 14 which is engaged with theinner cable 5. A return spring 3 biases the clutch pedal 2 in thedirection against the direction of pulling the inner cable 5, by bearingwith its one end on the vehicle body 36 and with its other end on thearm 4 of the clutch pedal 2. A stop 24 is also fixed to the vehiclebody, so as to oppose the movement of the arm 4 of the clutch pedal 2and stop it rotating in the direction against the direction of pullingthe inner cable 5 beyond a certain predetermined position.

The inner cable 5 extends through the outer pipe 7 to the actuatinglever 9 of the clutch. This clutch 1 is of a well known sort, andcomprises a flywheel 23 which is connected to an engine output shaft 27.A pressure plate 19 is mounted so as to oppose the flywheel 23 with aclutch facing 21 being between them. A circular spring or diaphragm 17normally biases the pressure plate 19 against the flywheel 23, thuspinching the clutch facing 21 between them, and ensuring transmission ofrotational power from the flywheel 23 to the clutch facing 21, which isrotationally connected to the output shaft 29. The release bearing 15 isso arranged that, when it is moved leftwards in the figure against thespring 17, it prevents pressure from being exerted by this spring 17 onthe pressure plate 19, thus releasing the pinching of the clutch facing21 and allowing the clutch to slip freely. This release bearing 15 isdriven by the lever 9, which is pivoted at its lower end in the drawingto the body of the clutch assembly, and whose upper end is, as alreadystated, connected to the end of the inner cable 5.

Thus, to recapitulate, when the inner cable 5 is pulled, by the clutchpedal assembly, so that its lower end in the drawing moves leftwards inthe drawing, it impels the lever 9 counter-clockwise, thus pushing therelease bearing 15 leftwards in the drawing, and allowing the clutch toslip, be deforming the spring 17 about the point 25, and thus stoppingthe spring 17 from biasing the pressure plate 19.

The upper and the lower ends of the outer cable 7 are braced against thebody of the automobile, and in the illustrated construction, the upperend is mounted adjustably, by several grooves 33 being formed on itsjoining portion, and by a circlip 35 being fitted into the grooves.

This kind of construction has several faults. The basic problems are:

(1) First, the inner cable 5 tends to stretch, which slackens it. Then,even if the clutch pedal 2 is completely depressed, it may occur thatthe clutch 1 does not slip completely, but drags; and, even if thisextreme position is not reached, the travel of the clutch pedal 2becomes unacceptably long. In other words, the point of control becomestoo low, and may be beyond the travel of the clutch pedal.

(2) Second, as the clutch facing 21 wears, the spring 17 moves leftwardsin the figure at its peripheral portions where it bears on the pressureplate 19, and therefore its inner portions move rightwards, so as tomove the release bearing 15 rightwards; in other words, if the releasebearing is moved from its extreme rightwards position in the figure toits extreme leftwards position, the point at which the clutch starts toslip becomes eariler and eariler, as the facing 21 wears. This has theeffect of tightening the cable 5, which is the opposite effect to thatdescribed under (1). These two effects, although they are opposed,usually do not cancel each other out. If this second effect is dominant,the point of control becomes too high, and may be beyond the travel ofthe clutch pedal 2 in its upward direction; in other words, the stop 24may prevent the clutch pedal 2 from being sufficiently raised to allowthe clutch 1 to grip firmly, and therefore the clutch 1 will tend toslip at all times.

The usual way to cope with these problems is to adjust the outer pipe 7,as shown in the illustration. However, this requires frequent visits toa maintenance facility, which is exceedingly troublesome.

Various structures have been proposed for example, in Jap. Pat. Pubs.23,128 and 23,129/77, and Jap. Utility Model. Pub. No. 44,499/73, forautomatically adjusting the effective length of the inner cable, withrespect to the outer pipe; however, they all have suffered from thedisadvantage that the adjustment has taken place in a stepwise fashion,for example by adjusting gear means, and is not continuous. Therefore,fine adjustment has not occurred, and when, for example, the adjustinggear means is not properly engaged, erratic clutch operation may perhapslead to an accident.

Similar clearance adjustment problems exist in other similar structures.

SUMMARY OF THE INVENTION

Therefore, it is an object of the present invention to provide aclearance adjuster which can smoothly and continuously take up clearancein an actuating system for driving a member which moves in such a waythat a first part of its travel is accomplished against a relatively lowresisting force and a second part of its travel is accomplished againsta relatively high resisting force.

It is another object of the present invention to provide an actuatingsystem with automatic clearance adjustment which is capable ofindefinitely fine adjustments.

It is a further object of the present invention to provide such anadjuster and such a system which can be manufactured cheaply and whichare very reliable and simple.

According to the present invention, these and other objects areaccomplished by a clutch actuation system for a vehicle which comprisesa first assembly adapted to be driven from a stop position by anactuating force, and a second assembly, which is driven by the firstassembly, and drives in a certain direction a driven member which movesin such a way that a first part of its travel is accomplished against arelatively weak resisting force, and a following part of its travel isaccomplished against a relatively strong restoring force.

A clearance adjuster comprises means for biasing the first and secondassemblies with respect to one another in such a direction as, if thefirst assembly remains in its stop position, to drive the driven memberin said certain direction with biasing force strong enough to overcomesaid relatively weak resisting force but not strong enough to overcomesaid relatively strong restoring force, and means for locking theposition of said first assembly with respect to said second assemblywhen said first assembly is moved off its stop position, and by meansfor locking the position of said first clearance adjusting member withrespect to said second clearance adjusting member when said forstactuator member is moved off its stop position.

A clutch device for a vehicles comprises a first assembly, adapted to bedriven from a stop position by an actuating force; a second assembly,which is driven by the first assembly, and which drives the drivenmember; means for biasing the first and second assemblies with respectto one another in such a direction as, if the first assembly remains inits stop postion, to drive the driven member in said certain directionwith biasing force strong enough to overcome said relatively weakresisting force but not strong enough to overcome said relatively strongrestoring force, and means for locking the position of said firstassembly with respect to said second assembly when said first assemblyis moved off its stop position.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects, features and advantages of the presentinvention will become more apparent from the following description ofthe preferred embodiments of the present invention taken in conjunctionwith the accompanying drawings in which:

FIG. 1 is a schematic view showing a prior art clutch system;

FIG. 2 is a schematic elevational view showing a clutch pedal deviceaccording to an embodiment of the present invention;

FIG. 3A is a perspective view showing a mechanism for adjusting theexpansion of the wire or cable employed in the clutch system accordingto the present invention;

FIG. 3B is a disassembled view of the frictional braking type adjustingmechanism as shown in FIG. 3A;

FIG. 4A shows a longitudinal section of the frictional damping typeadjusting mechanism as shown in FIG. 3A;

FIG. 4B is a section taken along B--B in FIG. 4A;

FIG. 5A is an end view showing a part of the adjusting mechanism asshown in FIG 3A;

FIG. 5B is a sectional veiw of the part as shown in FIG. 5A;

FIG. 6 is a schematic elevational view showing a clutch pedal assemblyaccording to another embodiment of the present invention;

FIG. 7A is a perspective view showing a mechanism for adjusting theexpansion of the inner cable employed in the clutch system as shown inFIG. 6;

FIG. 7B is a disassembled view of the adjusting mechanism as shown inFIG. 7A; and

FIG. 8 is a schematic elevational view showing a clutch pedal assemblyaccoring to a further embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 2, 3A and 3B, 4A and 4B, and 5A and 5B, there isshown a first preferred embodment of the present invention.

The clutch pedal assembly 2 illustrated is composed of two levers: apedal arm 4, which is hinged at its top end 10 about a shaft 8 fixed tothe vehicle body, and which is provided with a pedal pad 6 at its lowerend; and a lever 12, which is pivoted at its central portion 20 aboutthe shaft 8, whose top end is provided with a notch 14, to which aninner cable, not shown, which leads to a clutch mechanism similar tothat of FIG. 1, not shown, is attached, and whose bottom end 18 isjoined to a lash or clearance adjuster 16 which will be explainedhereinafter. The pedal arm 4 is biased in the direction to raise thepedal pad 6, by a spring 3.

The clearance adjuster 16 is connected between the lower end 18 of thelever 12, and the middle portion of the clutch pedal arm 4, to which itis joined by a pin 22. A part 26 of the clearance adjuster 16, to beexplained later, bears against a stop 24 which is attached to thevehicle body, when the pedal pad 6 rises up to a certain predeterminedheight, and thus stops the pedal pad from rising further.

Thus, the lever 12, the pedal arm 4, and the clearance adjuster 16 forma triangle, and the angle between the lever 12 and the pedal arm 4 canbe varied by the length of the clearance adjuster 16 varying.

The clearance adjuster 16 is shown in its assembled form in FIG. 3A, inan exploded view in FIG. 3B, and in sections in FIGS. 4A, 4B, 5A, and5B. It should be noted that FIG. 3B shows the adjuster before it isassembled, and hence the crimped constrictions 90 present in its outsideas seen in FIG. 3A, when it is assembled, are not visible in FIG. 3B,because they are introduced by a crimping tool during assembly.

Basically, this clearance adjuster 16 comprises two members, one beingattached to the pedal arm 4, and the other attached to the lever 12,further comprises means for biasing the members relative to one anotherin the direction which will, when the pedal arm remains in its stopposition, tension the inner cable 5--in other words, the direction toshorten the clearance adjuster 16 and turn the lever 12 clockwise inFIG. 2--and means for locking the positions of the members relative toone another, when the pedal arm moves off its stop position.

To embark upon constructional details, the cylindrical housing 30 ishinged to the pedal arm 4 by the pin 22 passing through the hole 32,near its left hand end in the figures. At its middle portion arectangular hole 34 is formed, to be explained later, and on either sideof this hole 34 the bushes 48 and 64 are crimped and fixed into thehousing 30 by constructions or crimps 90. The assembly of the housing 30and the bushes 48 and 64 therefore forms the first member, coupled tothe pedal arm 4.

The rod 36 is hinged to the lever 12 by its right hand end 44 in thedrawings being threaded and engaged with the threaded hole 78 of thebracket 42, through the hole 80 of which passes a pin, not designated byany reference number, which pivots the said bracket 42 to the lower end18 of the lever 12. The rod 36 passes through and along the tube 30, andits left hand end in the drawings is fitted with a circlip 38 whichrests in the groove 40. Thus the rod 36, bracket 42, and circlip 38 formthe second member.

The compression coil spring 46 is situated between the circlip 38 andthe bush 48, and by its compression biases the rod 36, relative to thetube 30, in the leftward direction in FIGS. 3 and 4, so as to make theclearance adjuster 16 shorter in axial length. This changes the shape ofthe triangle, mentioned above, formed of the clearance adjuster 16, thepedal arm 4, and the lever 12, so as to take up play in the cable 5 andtension it. It is arranged that the strength of the spring 46 issufficient to move the actuating lever 9 of FIG. 1 against the force ofthe spring 11 and the frictional force in the cable 5, but is notsufficient to move the lever 9 against the force of the spring 17.

Between the bushes 48 and 64 is mounted an arrangement for selectivelyfixing the relative positions of the rod 36 and the tube 30, when andonly when the pedal arm 4 is stepped on and the clutch pedal assemblymoves off its stop 24. In detail, this arrangement comprises a spring 62which is mounted around the rod 36, within the tube 30, and whose righthand end 68 in the figures is bent slightly outwards and is engaged inthe slot 66 of the bush 64. The left hand end of the spring 62 in thefigures is cut off square, and bears against a cutaway 60 on the righthand end in the figures of the push member 26 which is mounted betweenthe spring 62 and the bush 48. Thus, by rotating the push member 26 inthe direction around the rod 36 which will raise its projecting portion52 as seen in the figures, the spring 62 is slightly unwound, inaccordance with its direction of coiling as seen in the figures.

A slotted tube 70 is mounted around the spring 62 so as to keep itstraight within the tube 30. The flat projecting portion 52 of the pushmember 26 projects through the slot in the tube 70 and through the hole34 in the tube 30 to the outside, where it is adapted to bear on thestop 24, when the clutch pedal is not pressed, so that the pressure onthe stop 24 pushes the portion 52 upwards in the figures, thus, asexplained, uncoiling slightly the spring 62.

The spring 62 is of such a dimension that when it is not unwound itgrips tightly the rod 36.

As particularly seen in FIG. 5, the right hand bush 64 is formed with aleft hand portion 74 which is cut away to allow the right hand end ofthe spring 62 to enter it, and the bottom 76 of this portion 74 isslanted, as shown, along the direction of slant of the end of the spring62. The slot 66, mentioned above, is cut in the side of the portion 74.

In operation of this clearance adjuster 16, when the clutch pedal is notdepressed, then the portion 52 bears on the stop 24, and thereby, asexplained above, the spring 62 is slightly uncoiled, thus releasing itsgrip on the rod 36, and allowing this rod to move relatively to the tube30. This is because the force of the return spring 3 is greater thanthat of the coiling of the spring 62. The relative freedom of the rod 36and tube 30 allows the spring 46 to take up all the play in the clutchsystem, as explained above, by shortening the clearance adjuster 16.This compensates for lengthening of the cable 5, as explained above.Further, if the clutch facing 21 wears, then the release bearing 15moves rightwards in FIG. 1, and thereby the clearance adjuster 16becomes longer to compensate for this, since the spring 46 is not asstrong as the spring 17. Thus, in short, the clutch is properly adjustedby the spring 46, the two parts of the clearance adjuster 16 being freeto move relatively to one another.

When the clutch is pressed, and the portion 52 moves away from the stop24, then the resilience of the spring 62 coils it up again, so that itgrips tightly the rod 36 and prevents it from moving relative to thetube 30. Thus the clutch pulls firmly on the cable 5, because the lengthof the clearance adjuster 16 becomes fixed and constant as soon as thepedal is depressed. The more tensioning force is applied by the cable 5to lengthen the clearance adjuster 16, the more the end of the spring 62is pressed on the inclined face 76 of the bush 64, and thereby the morethe gripping force of the spring 62 on the rod 36 is increased. Thisgripping force is therefore increased in proportion to the increase intension load.

Whenever the clutch is pressed and released, this adjusting mechanismoperates, so that the clutch is always kept properly adjusted, with aninfinitely fine adjusting action.

FIGS. 6 and 7 show a second embodiment of the present invention, inwhich the push member 26 is omitted, and the end of the spring 62projects out through the hole 34. A lever 26' is pivoted on the bracket82 which is clamped around the tube 30, and the lever 26' has a slot 63into which the end of the spring 62 is fitted. The other end of thelever 26' bears on the stop 24. It will be seen that the same functionsand advantages are available with this construction.

FIG. 8 shows schematically a third embodiment of the present invention,in which the clearance adjuster is not in tension, but in compression.In this case, the spring 46' is provided between the clearance adjusterand the bracket 42', as seen from the figure, and tends to lengthen theclearance adjuster, rather than, as in the first and second embodiments,to shorten it. It will be seen that the same functions and advantagesare available with this construction, also.

The present invention, therefore, provides a clearance adjuster, and/oran actuator, of simple and durable construction, which is independentlyarranged as one unit, and has no forged or cast parts (thereby beingcheap to make and light), which automatically adjusts the length of thecable, with indefinitely fine adjustment available.

Although the present invention has been shown and described withreference to some preferred embodiments thereof, it should be understoodthat various alterations in the form and the content of any particularembodiment may be made without departing from the scope of theinvention.

We claim:
 1. For a clutch actuation system for a vehicle which comprisesa first assembly adapted to be driven from a stop position by anactuating force, and a second assembly, which is driven by the firstassembly, and drives in a certain direction a driven member which movesin such a way that a first part of its travel is accomplished against arelatively weak resisting force, and a following part of its travel isaccomplished against a relatively strong restoring force,a clearanceadjuster, comprising: means for biasing the first and second assemblieswith respect to one another in such a direction as, if the firstassembly remains in its stop position, to drive the driven member insaid certain direction with biasing force strong enough to overcome saidrelatively weak resisting force but not strong enough to overcome saidrelatively strong restoring force; and means for locking the position ofsaid first assembly with respect to said second assembly when said firstassembly is moved off its stop position.
 2. For a clutch actuationsystem for a vehicle which comprises a first actuator member adapted tobe driven from a stop position by an actuating force, and a secondactuator member, which is driven by the first actuator member, anddrives in a certain direction a driven member which moves in such a waythat a first part of its travel is accomplished against a relativelyweak resisting force, and a following part of its travel is accomplishedagainst a relatively strong restoring force,a clearance adjuster, whichcouples the first actuator member to drive the second actuator member,comprising: a first clearance adjuster member coupled to the firstactuator member; a second clearance adjuster member coupled to thesecond actuator member; means for biasing the first and second clearanceadjuster members with respect to one another in such a direction as, ifthe first actuator member remains in its stop position, to drive thedriven member in said certain direction with biasing force strong enoughto overcome said relatively weak resisting force but not strong enoughto overcome said relatively strong restoring force; and means forlocking the position of said first clearance adjusting member withrespect to said second clearance adjusting member when said firstactuator member is moved off its stop position.
 3. A clutch device for avehicle, comprising:a first assembly, adapted to be driven from a stopposition by an actuating force; a second assembly, which is driven bythe first assembly, and which drives the driven member; means forbiasing the first and second assemblies with respect to one another insuch a direction as, if the first assembly remains in its stop position,to drive the driven member in said certain direction with biasing forcestrong enough to overcome said relatively weak resisting force but notstrong enough to overcome said relatively strong restoring force; andmeans for locking the position of said first assembly with respect tosaid second assembly when said first assembly is moved off its stopposition.
 4. A clutch system for a vehicle, comprising:a first actuatormember, adapted to be driven from a stop position by an actuating force;a second actuator member, which is driven by the first actuator member,and drives the driven member; a first clearance adjuster member which iscoupled to and driven by the first actuator member; a second clearanceadjuster member which is coupled to and drives the second actuatormember; means for biasing the first and second clearance adjustermembers with respect to one another in such a direction as, if the firstactuator member remains in its stop position, to drive the driven memberin said certain direction with biasing force strong enough to overcomesaid relatively weak resisting force but not strong enough to overcomesaid relatively strong restoring force; and means for locking theposition of said first lash adjuster member with respect to said secondclearance adjuster member when said first actuator member is moved offits stop position.
 5. A clutch system as in claim 1, further comprisinga stop; the actuator's first assembly comprising a first actuator memberand a first clearance adjuster member coupled to the first actuatormember; the actuator's second assembly comprising a second actuatormember which drives the driven member and a second clearance adjustermember coupled to the second actuator member; wherein the biasing meanscomprises a spring which acts between the first and the second clearanceadjuster members; wherein one of the first and the second clearanceadjuster members comprises a rod, and the other comprises a tube fittedover the rod; and wherein the locking means comprises a coil springwound around the rod and held within the tube and substantially fixed inthe longitudinal direction with respect to the tube, with its one endsubstantially fixed in the circumferential direction of the tube andwith its other end actuated to move substantially in the circumferentialdirection of the tube by the stop, when the first assembly is in itsstop position, so as to uncoil the coil spring so that the coil springis loosely fitted over the rod; the coil spring, when its said other endis not actuated by the stop, coiling up under its own resilience so asto grip the rod.
 6. A clutch system as claim 2, further comprising astop; wherein the biasing means comprises a spring which acts betweenthe first and the second clearance adjuster members; wherein one of thefirst and the second clearance adjuster members comprises a rod, and theother comprises a tube fitted over the rod; and wherein the lockingmeans comprises a coil spring wound around the rod and held within thetube and substantially fixed in the longitudinal direction with respectto the tube, with its one end substantially fixed in the circumferentialdirection of the tube and with its other end actuated to movesubstantially in the circumferential direction of the tube by the stop,when the first actuator member is in its stop position, so as to uncoilthe coil spring so that the coil spring is loosely fitted over the rod;the coil spring, when its said other end is not actuated by the stop,coiling up under its own resilience so as to grip the rod.
 7. A clutchdevice as in claim 3, further comprising a stop; the first assemblycomprising a first actuator member and a first clearance adjuster membercoupled to the first actuator member; the second assembly comprising asecond actuator member which drives the driven member and a secondclearance adjuster member coupled to the second actuator member; whereinthe biasing means comprises a spring which acts between the first andthe second clearance adjuster members; wherein one of the first and thesecond lash adjuster members comprises a rod, and the other comprises atube fitted over the rod; and wherein the locking means comprises a coilspring wound around the rod and held within the tube and substantiallyfixed in the longitudinal direction with respect to the tube, with itsone end substantially fixed in the circumferential direction of the tubeand with its other end actuated to move substantially in thecircumferential direction of the tube by the stop, when the firstassembly is in its stop position, so as to uncoil the coil spring sothat the coil spring is loosely fitted over the rod; the coil spring,when its said other end is not actuated by the stop, coiling up underits own resilience so as to grip the rod.
 8. A clutch device as in claim4, further comprising a stop; wherein the biasing means comprises aspring which acts between the first and the second clearance adjustermembers; wherein one of the first and the second clearance adjustermembers comprises a rod, and the other comprises a tube fitted over therod; and wherein the locking means comprises a coil spring wound aroundthe rod and held within the tube and substantially fixed in thelongitudinal direction with respect to the tube, with its one endsubstantially fixed in the circumferential direction of the tube andwith its other end actuated to move substantially in the circumferentialdirection of the tube by the stop, when the first actuator member is inits stop position, so as to uncoil the coil spring so that the coilspring is loosely fitted over the rod; the coil spring, when its saidother end is not actuated by the stop, coiling up under its ownresilience so as to grip the rod.
 9. A clutch system as in claim 5 or 6,wherein the locking means further comprises a push member which isadapted to bear on the stop so as to drive said other end of the coilspring.
 10. A clutch system as in claim 5 or 6, wherein said other endof the coil spring is adapted to bear directly on the stop.
 11. A clutchdevice as in claim 7 or 8, wherein the locking means further comprises apush member which is adapted to bear on the stop so as to drive saidother end of the coil spring.
 12. A clutch device as in claim 7 or 8,wherein said other end of the coil spring is adapted to bear directly onthe stop.